I think it's bizarre that you don't think it normal that a superpower contain those threatening it.
The World has always had, and will continue to have, countries that are stronger than others. These stronger countries will try to exert their influence, it's human nature. We should be thankful we live in a time where the current superpower is quite close to us culturally, as well as militarily.
Have you considered what an uncontained China, left alone to rum rampant throughout Asia & the Pacific, might look like for Australian interests?
You referenced WW2 in your post. The Yanks tried sitting that one out early on, how did that work out? They lost 400,000 soldiers. The principle of containment is centered around avoiding a hot war, where hundreds of thousands if not millions would be lost. There always will be conflict, the question becomes what type of conflict do you want, and on what terms?
